Consider you have a set of data that is changing dynamically for each page request and you need to cache that data the fastest way possible. You can't cache dynamic and unpredictable data as a whole, can you? Hence, we would put each data entry into cache separately to be able to fetch it separately and dynamically. But this means bombing your cache infrastructure with with requests.

They break it up into a few different topics - caching text elements on the page, two-tiered caching (grouping cached items), incremental caching and cache versioning. They don't share an example of their code unfortunately, but they do mention something about a possible contribution to the Zend_Cache component of the Zend Framework.